My wife gets gas receipts, leaves them in the car for a few days then throws them away. I asked her why she kept getting receipts if she was just going to throw them away. She said it was in case somebody accused her of driving away from the pump without paying she would have proof that she paid. I asked her how many times that had happened to her or if she had EVER heard of it happening to anybody and she said no - but she still does it. Not to mention the credit card transaction is all the proof you need.